Consideration has been given to using single color LED's, such as red, blue or green LED's, in combination with fluorescent and phosphorescent materials to produce another desired color. While certain materials respond fluorescently or phosphorescently to light from the visible portion of the spectrum, and thus would respond to visible LED's, there are a number of materials which respond to the relatively higher-energy photons emitted in the ultraviolet portion of the spectrum. Furthermore, UV-emitting LED's may, in combination with the appropriate phosphor, prove to be a source of white light providing a high level of satisfaction. That is, white light generated from a UV LED and accompanying phosphor may lack the artifacts of a colored light source employed to produce light from an LED emitting in the colored portion of the visible spectrum. For example, this phenomenon is believed to affect blue LED's when used to excite a phosphor during production of white light, where the generated white light is believed to exhibit a blue component. Accordingly, recent interest has focused upon the use of a UV-emitting LED.
At least certain prior art LED devices emit light in directions that may be undesirable, such as through the sides of the diode, as opposed to only substantially through the preferred side for the emission of energy. Depending upon the end use for which the LED is employed, this may not be a problem. However, as indicated, there may be instances where emissions in undesired directions have substantial unwanted consequence. For example, in UV-induced fluorescence detection applications, stray UV light can dramatically increase the background noise in the photodetection of fluorescent light. Further, in such application, it is preferred that a focused beam of UV light is provided to generate sufficient fluorescence for localized photodetection. At the very least, emissions in undesired directions may be indicative of an inefficient device.